In some rotary earth drills, particularly of the coring type, drill bit sockets or pockets are welded to and spaced around side surfaces of a drill head. Drill bits with shanks shaped complementarily to the bore or socket of the drill sockets are held in position in the sockets by pins that extend through holes or a channel in the drill bit shank and through holes in the side wall of the socket.
The bits are expected to wear and to be replaced, which is easily accomplished by pulling the pin and installing a new bit. However, when the socket itself becomes worn, eroded by the often abrasive materials through which it passes and in which it rotates, its replacement requires that the drill head itself substantially be rebuilt. The old socket has to be cut away and a new one welded into place. This is time consuming and expensive.
One of the objects of this invention is to provide a way to protect the sockets from wear. Other objects will become apparent to those skilled in the art in the light of the following disclosure and accompanying drawing.